Semiconductor component comprising magnetic field sensor

ABSTRACT

The invention relates to a semiconductor component ( 100 ) comprising a semiconductor chip ( 10 ) configured as a wafer level package, a magnetic field sensor ( 11 ) being integrated into said semiconductor chip.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 11/608,507, filed Dec. 8, 2006. The aforementioned relatedpatent application is herein incorporated by reference in its entirety.

DESCRIPTION

Semiconductor component comprising a magnetic field sensor

The invention relates to a semiconductor component comprising a magneticfield sensor. The invention furthermore relates to a method forproducing a semiconductor component of this type.

Semiconductor components comprising magnetic field sensors are used e.g.as position sensors or rate-of-rotation sensors. By way of example,semiconductor components of this type are integrated into clamshelltelephones or into doors or the surroundings thereof in order to be ableto ascertain whether the clamshell telephone or the door is open orclosed.

Against this background, a semiconductor device in accordance with theindependent claims 1, 11 and 26 and also a method in accordance with theindependent claim 18 are specified. Advantageous developments andconfigurations are specified in the subclaims.

In accordance with one configuration, a semiconductor componentcomprises a semiconductor chip configured as a wafer level package. Amagnetic field sensor is integrated into the semiconductor chip.

In accordance with a further configuration, a semiconductor componentcomprises a semiconductor chip, into which a magnetic field sensor isintegrated, and external contact elements. The external contact elementsare applied to an active main surface of the semiconductor chip.

In accordance with a further configuration, a semiconductor componentcomprises a semiconductor chip, into which a magnetic field sensor isintegrated, and a magnet applied to a first main surface of thesemiconductor chip.

In accordance with a further configuration, a carrier is provided, whichcomprises a plurality of integrated circuits. At least one first one ofthe integrated circuits comprises a magnetic field sensor. Externalcontact elements are applied to a main surface of the carrier. Theintegrated circuits are singulated after the application of the externalcontact elements.

The invention is explained in more detail below in exemplary fashionwith reference to the drawings, in which:

FIG. 1 shows a schematic illustration of a semiconductor component 100as an exemplary embodiment of the invention;

FIG. 2 shows a schematic illustration of a semiconductor component 200as a further exemplary embodiment of the invention;

FIG. 3 shows a schematic illustration of the semiconductor component 200arranged on a printed circuit board 17;

FIG. 4 shows a schematic illustration of a semiconductor component 300as a further exemplary embodiment of the invention;

FIG. 5 shows a schematic illustration of a semiconductor component 400as a further exemplary embodiment of the invention;

FIGS. 6A to 6D show schematic illustrations of a method for producingthe semiconductor component 200 as a further exemplary embodiment of theinvention;

FIG. 7 shows a schematic illustration of a semiconductor component 500as a further exemplary embodiment of the invention;

FIGS. 8A and 8B show schematic illustrations of the magnetic field lines27 generated by the semiconductor component 400;

FIG. 9 shows a schematic illustration of an application of thesemiconductor component 400 as a rate-of-rotation sensor;

FIG. 10 shows a schematic illustration of a magnetic field sensor 1000integrated into a semiconductor component;

FIG. 11 shows a micrograph of a part of a magnetic field sensor; and

FIG. 12 shows a schematic illustration of a magnetic field sensor and anevaluation circuit.

Semiconductor components comprising semiconductor chips which havemagnetic field sensors are described below. The invention is independentof the type of magnetic field sensors. By way of example, the magneticfield sensors may be Hall elements or GMR sensors, which utilize theHall effect or the GMR (Giant MagnetoResistance) effect, respectively,for measuring a magnetic field. The magnetic field sensors can measurefor example an absolute defining quantity of a magnetic field, such ase.g. the magnetic field strength or changes in a magnetic field.

In accordance with one configuration, the semiconductor chip, into whicha magnetic field sensor is integrated, is formed as a Wafer LevelPackage (WLP). In this case, the term “Wafer Level Package” relates tosemiconductor chips having one active main surface that has beenpopulated at the wafer level with external contact elements that arerequired for subsequently making contact with a printed circuit board.The semiconductor chips (dies) have been singulated only after theapplication of the external contact elements. After singulation, a WLPcan be mounted onto a printed circuit board without significant furtherprocessing of the main surface. In particular, mounting of the WLPs ontoan interposer or a leadframe and potting of the individual WLPs with apotting material are no longer necessary. Potting material also need notsubsequently be filled into the interspace between WLP and printedcircuit board (“underfill”). WLPs are therefore distinguished by smallsize, small weight and no production costs.

Since the dimensions of a wafer level package are either equal inmagnitude to those of the semiconductor chip or only insignificantlylarger, an expression that is also often used is chip size packages orchip scale packages. A chip size package is approximately the same sizeas the semiconductor chip, while a chip scale package is up to 30%larger than the semiconductor chip.

In accordance with one configuration, the active main surface of thesemiconductor chip is provided with external contact elements. Activemain surface is to be understood to mean the surface of thesemiconductor chip on or in which e.g. the magnetic field sensor orelectrically operable structures or circuits are situated. The externalcontact elements may comprise e.g. metalized contact areas, underbumpmetalizations or solder deposits, for example in the form of solderballs. The external contact elements are provided for making electricalcontact with the semiconductor chip externally. At the same time, theexternal contact elements may serve for holding the semiconductor chipmechanically in a fixed position in relation to a conductor tracksubstrate, e.g. a PCB board (Printed Circuit Board), or ceramic. By wayof example, the semiconductor chip is mounted in a flip-chip positiononto a printed circuit board and the external contact elements producean electrical connection between the semiconductor chip and the printedcircuit board.

FIG. 1 illustrates a semiconductor component 100 in cross section as anexemplary embodiment of the invention. The semiconductor component 100has a semiconductor chip 10, into which a magnetic field sensor 11 isintegrated. Furthermore, the semiconductor component 100 has externalcontact elements arranged on an active main surface 12 of thesemiconductor chip 10, said external contact elements comprising astructured metalization layer 13 and underbump metalizations 14 in thecase of the semiconductor component 100.

The magnetic field sensor 11 integrated into the semiconductor chip 10is designed to measure a magnetic field or changes in a magnetic field.For this purpose, the magnetic field sensor 11 may measure a quantitydefining the magnetic field, such as e.g. the magnetic field strength,or changes in such a quantity. Furthermore, the magnetic field sensor 11may be configured in such a way that it ascertains whether or not themagnetic field prevailing at the location of the magnetic field sensor11 exceeds a predetermined threshold value. By way of example, themagnetic field sensor 11 may be a Hall element or a GMR sensor, whichutilizes the Hall effect or the GMR effect, respectively, for measuringthe magnetic field. The semiconductor chip 10 may contain circuits whichdrive the magnetic field sensor 11 and/or evaluate measurement signalsrecorded by the magnetic field sensor 11. As an alternative, control andevaluation circuits of this type may also be integrated into a furthersemiconductor chip that interacts with the semiconductor chip 10.Furthermore, the semiconductor chip 10 may be configured for example asa position and/or rate-of-rotation sensor.

The active main surface 12 has contact elements which can be used tomake electrical contact with the electrically operable structures orcircuits. The structured metalization layer 13 is deposited on thecontact elements of the active main surface 12. The structuredmetalization layer 13 may comprise a metal such as e.g. aluminium,copper or gold, or an electrically conductive alloy.

Furthermore, a passivation layer 15 comprising a polymer-containingmaterial, for example, is deposited on the active main surface 12 of thesemiconductor chip 10. The passivation layer is typically 5 μm to 20 μmthick and may for example also comprise a plurality of layers. It servesto protect the active main surface 12 against environmental influencessuch as e.g. dirt, moisture or else mechanical impacts. The passivationlayer 15 has been opened in the regions of the structured metalizationlayer 13 by means of photolithographic methods, with the result thatsaid regions are available for externally making contact with thesemiconductor chip 10. The underbump metalizations 14 are applied to theuncovered regions of the structured metalization layer 13.

The underbump metalizations 14 may serve for example as an adhesionpromoter for the solder material that is to be applied later.Furthermore, the underbump metalizations 14 may be provided for forminga diffusion barrier that prevents the material of the structuredmetalization layer 13 from diffusing into the solder material. A furthertask of the underbump metalizations 14 may be to reduce the contactresistance between the structured metalization layer 13 and the soldermaterial. AlNiVCu, TiW, Au, Ni and NiP shall be mentioned, by way ofexample, as materials for the underbump metalizations 14. The underbumpmetalizations 14 may be deposited and structured for example likemetalization layers.

Solder deposits, for example in the form of solder balls 16, may beapplied to the underbump metalizations 14. This is illustrated in FIG.2. The semiconductor component 200 shown therein as a further exemplaryembodiment of the invention corresponds to the semiconductor component100 otherwise. The suitable solder material includes alloys composed forexample of the following materials: SnPb, SnAg, SnAgCu, SnAgCuNi, AuSn,CuSn and SnBi. The solder balls 16 are applied by means of so-called“ball placement”, for example, in which preformed balls made of soldermaterial are applied to the underbump metalizations 14. The adhesionbetween the solder balls 16 and the underbump metalizations 14 isbrought about by a flux that has been printed on beforehand by means ofstencil printing. The application of the solder balls 14 may be followedby a thermal process (reflow) in which the solder material melts andwets the contact elements. As an alternative to the “ball placement”,the solder balls may be applied for example by means of stencil printingwith a solder paste with a subsequent thermal process (reflow) or byelectroplating and optional subsequent thermal process (reflow).

In the case of the semiconductor component 100, the semiconductor chiptogether with the external contact elements comprising the structuredmetalization layer 13 and the underbump metalizations 14 forms a waferlevel package. In the case of the semiconductor component 200, theexternal contact elements additionally also contain the solder balls 16.In the case of a wafer level package, the external contact elements areapplied to the active main surface 12 of the semiconductor chip 10 at apoint in time at which the semiconductor chip 10 is still part of asemiconductor wafer. It is only in a later work step that thesemiconductor chip 10 is separated from the semiconductor wafer. Such aproduction method will be explained in greater detail further below inconnection with FIG. 6.

The semiconductor component 100 or 200 can be mounted onto a printedcircuit board or some other substrate. This is illustrated using theexample of the semiconductor component 200 in FIG. 3. The semiconductorcomponent 200 is mounted onto a printed circuit board 17 in a flip-chipposition, that is to say that the active main surface 12 of thesemiconductor chip 10 faces the printed circuit board 17. Solderingconnections between the semiconductor chip 10 and contact elements 18 ofthe printed circuit board 17 were produced by means of the solder balls16.

In the case of the arrangement shown in FIG. 3, the interspace betweenthe semiconductor component 200 and the printed circuit board 17 is notfilled with a potting composition, such as e.g. a plastic material orglobe top, that is to say that a so-called underfill is not introducedbetween the semiconductor component 200 and the printed circuit board17.

The semiconductor components 100 and 200 can be produced in a simple andcost-effective manner with the aid of wafer level packagingtechnologies. Cost-effective wafer processes can be used for fabricatingthe external contact elements and otherwise customary steps forproducing a housing, such as e.g. encapsulation with a pottingcomposition by injection moulding, can be obviated. Furthermore, thesemiconductor components 100 and 200 have a compact size, so that theycan be integrated into application devices, such as e.g. telephones, ina space-saving manner

A rewiring layer may optionally be arranged between the active mainsurface 12 of the semiconductor chip 10 and the metalization layer 13.The rewiring layer serves for connecting the contact elements integratedinto the active main surface 12 to the external contact elements, if theexternal contact elements are not situated directly above the contactelements of the active main surface 12. Accordingly, any desiredarrangement of the external contact elements is made possible by meansof a rewiring layer. The rewiring layer comprises conductor tracksleading from the contact elements of the active main surface 12 to thedesired locations for the external contact elements. If appropriate,further insulation layers may be provided above and/or below therewiring layer.

FIGS. 4 and 5 show semiconductor components 300 and 400 representingdevelopments of the semiconductor components 100 and 200. In bothsemiconductor components 300 and 400, a magnet was applied to therespective wafer level package. The semiconductor component 300 has amagnet 19 on the passivation layer 15 directly above the magnetic fieldsensor 11. In the case of the semiconductor component 400, a magnet 20was applied to the rear side of the semiconductor chip 10.

The magnets 19 and 20 serve to generate a magnetic field at the locationof the magnetic field sensor 11. This makes it possible to detect theapproach of a magnet or of soft-magnetic materials having low coercivefield strengths to the magnetic field sensor 11. If a magnet or asoft-magnetic material is brought into the vicinity of the magneticfield sensor 11, then the magnetic field generated by the magnet 19 or20 changes as a result. This change can be detected by the magneticfield sensor 11. One advantage of the semiconductor components 300 and400 is that the magnets 19 and 20 are situated very close to themagnetic field sensor 11. This increases the sensitivity of the magneticfield sensor 11.

Soft-magnetic materials may be for example alloys composed of iron,nickel or cobalt.

The magnets 19 and 20 may be for example integral permanent magnetshaving a permanent magnetization. The permanent magnets may be mountedonto the front or rear side of the semiconductor chip 10, e.g. byadhesive bonding. The permanent magnets may comprise anypermanent-magnetic material, such as e.g. AlNiCo alloys, FeTb alloys,ferrite compounds, rare earths, samarium or neodymium.

As an alternative to an integral permanent magnet, a permanent-magneticthin layer may be applied on the front or rear side of the semiconductorchip 10, e.g. by sputtering, vapour deposition or electrodeposition. Byway of example, the same materials as for the integral permanent magnetsmay be used as materials for the permanent-magnetic thin layers.

A permanent-magnetic layer is often only weakly magnetized afterdeposition onto the semiconductor chip 10. Therefore, it may benecessary to magnetize the layer after deposition. By way of example,for this purpose the semiconductor components 300 or 400 may be exposedto a sufficiently high magnetic field during a heat treatment step. Inthis case, the orientation of the magnetization may also be influencedunder certain circumstances.

FIGS. 6A to 6D schematically illustrate a method for producing thecomponent 200 as an exemplary embodiment of the invention. The methodinvolves firstly providing a carrier 21, into which a plurality ofcircuits are integrated. Said circuits include the magnetic field sensor11 and possibly further circuits which the semiconductor chip 10comprises. The carrier 21 may be for example a semiconductor wafer 21,e.g. a silicon wafer.

As is shown in FIG. 6A, the structured metalization layer 13, and alsothe passivation layer 15 is applied to the active main surface 12 of thesemiconductor wafer 21. If appropriate, a rewiring layer may also beapplied to the semiconductor wafer 21. The underbump metalizations 14(cf. FIG. 6B) and the solder balls 16 (cf. FIG. 6C) are subsequentlyapplied. Furthermore, it is possible to apply the magnets 19 or 20whilst still at the wafer level. Since wafer process technologies canstill be used in this production stage, it is particularly favourable inrespect of outlay to deposit a permanent-magnetic thin layer on theactive main surface 12 of the semiconductor wafer 21. This furthermorehas the advantage that the permanent-magnetic layer is situated indirect proximity to the magnetic field sensor 11.

After the application of the external contact elements, which in FIG. 6comprise the structured metalization layer 13, the underbumpmetalizations 14 and the solder balls 16, to the active main surface 12of the semiconductor wafer 21, the individual semiconductor chips of thesemiconductor wafer 21 can be singulated, e.g. by sawing.

FIG. 7 illustrates a semiconductor component 500 in cross section as afurther exemplary embodiment of the invention. In contrast to thesemiconductor components 100 to 400, the semiconductor component 500 isnot a wafer level package. As is shown in FIG. 7, the semiconductor chip10, into which the magnetic field sensor 11 is integrated, was mountedonto a carrier 22, for example a die pad of a leadframe that is composedof sheet copper. The active main surface 12 of the semiconductor chip 10is oriented upwards in this case. The contact elements of the activemain surface 12 are connected to external contact elements 24 viaconnecting lines 23, in particular bonding wires. Electrical contact canbe made with the semiconductor chip 10 from outside the semiconductorcomponent 500 via the external contact elements 24. The external contactelements 24 may be e.g. metallic pins of a leadframe. As is shown inFIG. 7, the pins 24 may be angled in order that they can be applied to aprinted circuit board and be soldered there.

A magnet 25 is applied to the active main surface 12 of thesemiconductor chip 10. The magnet 25 may be configured just like themagnets 19 and 20 of the semiconductor components 300 and 400,respectively, described above. Consequently, the magnet 25 may be anintegral permanent magnet that is adhesively bonded to the semiconductorchip 10, for example, or a permanent-magnetic thin structured layer maybe deposited on the semiconductor chip 10.

As is shown in FIG. 7, the carrier 22 and also the components arrangedon the carrier 22 are integrated together with the magnet 25 into ahousing. The housing may comprise a potting material 26, e.g. a plasticmaterial, which envelops a carrier 22 and also the components arrangedthereon. Only the ends of the pins 24 were left free in order to enablecontact to be made with the semiconductor chip 10 externally.

One advantage of the semiconductor component 500 is that the magnet 25is situated in direct proximity to the magnetic field sensor 11 justlike in the case of the semiconductor components 300 and 400.

As an alternative to the contact-making by means of wire bondingtechnology as shown in FIG. 7, contact can be made with thesemiconductor chip 10 by means of a flip-chip technology, too.

FIGS. 8A and 8B show exemplary orientations of the magnetic fieldgenerated by the magnet 20 of the semiconductor component 400. For thispurpose, schematic magnetic field lines 27 are depicted in FIGS. 8A and8B. In FIG. 8A, the magnet 20 is magnetized perpendicular to the activemain surface 12 of the semiconductor chip 10, while in FIG. 8B themagnetization is oriented parallel to the active main surface 12.

In the case of an integral permanent magnet 20, the orientation of themagnetic field 27 generated by it can be determined by a correspondingorientation of the permanent magnet 20. If the magnet 20 is produced bydeposition of a thin permanent-magnetic layer, there is a possibility,in principle, of setting a desired orientation of the magnetic field 27by means of a subsequent magnetization step. This is not possible,however, for all permanent-magnetic materials. If e.g. a perpendicularorientation of the magnetic field 27 is required for a specificapplication (cf. FIG. 8A), a material which exhibits an intrinsicperpendicular anisotropy in layer form can be chosen for the thinpermanent-magnetic layer deposited on the semiconductor chip 10. Such anintrinsic perpendicular anisotropy is exhibited by FeTb alloys, forexample.

FIG. 9 illustrates by way of example an application of the semiconductorcomponent 400 as a rate-of-rotation sensor. The semiconductor component400 is mounted onto a printed circuit board 28 in a flip-chip position.Soldering connections between the semiconductor component 400 andcontact elements 29 of the printed circuit board 28 were produced bymeans of the solder balls 26. A gearwheel 30 made of a soft-magneticmaterial having a low coercive field strength is arranged within themagnetic field 27 generated by the magnet 20. Upon rotation of thegearwheel 30, the magnetic field 27 changes periodically on account ofthe structure of the gearwheel 30, as is shown in FIG. 9. Such changesin the magnetic field 27 are measured by the magnetic field sensor 10.An evaluation circuit integrated into the semiconductor chip 10 candetermine the rate of rotation of the gearwheel 30 on the basis of theperiodically recurring measurement data supplied by the magnetic fieldsensor 10.

In the application in accordance with FIG. 9, an orientation of themagnetization of the magnet 20 perpendicular to the active main surface12 is favourable since it is thereby possible to detect changes in themagnetic field 27 with a high accuracy.

In the application of the semiconductor components described here, amagnet need not necessarily be integrated into the semiconductorcomponent. By way of example, it may also be provided that a magnet isfixed to a counter-workpiece and the magnetic field sensor 10 measureswhether or not the counter-workpiece is situated in the vicinity of thesemiconductor component or whether or not the counter-workpiece isapproaching the semiconductor component. Instead of measuring the rateof rotation of a rotating gearwheel, this application may also be usedfor measuring angles of rotation of rotary articulations, e.g. inclamshell telephones or in the surroundings of doors. It is thuspossible to ascertain whether the clamshell telephone or a door is openor closed.

FIG. 10 schematically illustrates the cross section through asemiconductor component into which a magnetic field sensor 1000 isintegrated. By way of example, the magnetic field sensors 11 may beintegrated into the semiconductor components 100 to 500 in a similarmanner. The magnetic field sensor 1000 utilizes e.g. the GMR effect formeasuring a magnetic field. Spin valve sensors, in which thinsoft-magnetic layers are separated from one another by non-magneticlayers, constitute one possibility for utilizing the GMR effect. Thedirection of the magnetization of at least one of the soft-magneticlayers is fixed by suitable means, for example an antiferromagneticlayer. The magnetizations of the other soft-magnetic layers can rotatefreely in a magnetic field applied from outside the semiconductorcomponent. The fact that the electrical resistance between thesoft-magnetic layers depends on the angle between the magnetizations ofthe individual layers is utilized for measurement of the externalmagnetic field.

FIG. 10 shows that metalization layers 1002 and 1003 are applied to asemiconductor chip 1001, said metalization layers being connected to oneanother by via connections. The magnetic field sensor 1000 is arrangedthereabove, said magnetic field sensor having been coated with apassivation layer 1004.

FIG. 11 shows a micrograph—recorded by a microscope—of a GMR magneticfield sensor integrated into a semiconductor component for themeasurement of angles of rotation. The GMR magnetic field sensor has twofull bridges 1005 and 1006, which are offset by 90°. Each of the fullbridges 1005 and 1006 comprises two series-connected half-bridges eachhaving a meandering structure. The two full bridges 1005 and 1006 are ineach case connected up as a Wheatstone bridge. Each of the two fullbridges 1005 and 1006 enables the unambiguous assignment to an angularrange of 180°. The use of two full bridges 1005 and 1006 offset by 90°makes it possible to cover the full 360° range with the aid of an arctancalculation.

FIG. 12 shows an evaluation circuit for evaluating the measurementsignals supplied by the full bridges 1005 and 1006. A digital signalprocessor (DSP) serves to execute the required calculations in order toconvert the signal into an angle in the 360° range after an offsetsubtraction. The evaluation circuit illustrated in FIG. 12 can beintegrated together with the GMR magnetic field sensor onto asemiconductor chip.

What is claimed is:
 1. Semiconductor component comprising a semiconductor chip configured as a wafer level package, a magnetic field sensor being integrated into said semiconductor chip.
 2. Semiconductor component according to claim 1, wherein a magnet is applied to a first main surface of the semiconductor chip.
 3. Semiconductor component according to claim 2, wherein the magnet is a layer made of a permanent-magnetic material that is deposited on the first main surface of the semiconductor chip.
 4. Semiconductor component according to claim 2, wherein the magnet is an integral permanent magnet mounted onto the first main surface of the semiconductor chip.
 5. Semiconductor component according to claim 2, 20 wherein the first main surface is the active main surface ofthe semiconductor chip.
 6. Semiconductor component according to claim 1, wherein external contact elements are applied to the active main surface of the semiconductor chip.
 7. Semiconductor component according to claim 6, wherein the external contact elements have an underbump metallization.
 8. Semiconductor component according to claim 6, wherein the external contact elements have solder deposits arranged in particular in flip-chip-like fashion.
 9. Semiconductor component according to claim 6, wherein a rewiring layer is arranged between the semiconductor chip and the external contact elements.
 10. Semiconductor component according to claim 1, wherein the semiconductor chip is configured as a position sensor or rate-of-rotation sensor or as a part of a position sensor or rate-of-rotation sensor.
 11. Semiconductor component comprising: a semiconductor chip, into which a magnetic field sensor is integrated, and external contact elements applied to an active main surface of the semiconductor chip.
 12. Semiconductor component according to claim 11, wherein a magnet is applied to a first main surface of the semiconductor chip.
 13. Semiconductor component according to claim 12, wherein the magnet is a layer made of a permanent-magnetic material that is deposited on the first main surface of the semiconductor chip.
 14. Semiconductor component according to claim 12, wherein the magnet is an integral permanent magnet mounted onto the first main surface of the semiconductor chip.
 15. Semiconductor component according to claim 11, wherein the external contact elements have an underbump metalization.
 16. Semiconductor component according to claim 11, wherein the external contact elements have solder deposits arranged in particular in flip-chip-like fashion.
 17. Semiconductor component according to claim 11, wherein a rewiring layer is arranged between the active main surface of the semiconductor chip and the external contact elements.
 18. Method in which a carrier is provided, which comprises a plurality of integrated circuits, wherein at least one first one of the integrated circuits comprises a magnetic field sensor, external contact elements are applied to a main surface of the carrier, and the integrated circuits are singulated after the application of the external contact element.
 19. Method according to claim 18, wherein the carrier is a semiconductor wafer.
 20. Method according to claim 18, wherein the magnetic field sensor and the external contact elements are arranged at the same main surface of the carrier. 21-32. (canceled) 